Polymeric organic materials with the ability to conduct electricity were first characterised in the 1960s by D. E. Weiss and coworkers. In 2000 the Nobel Prize for Chemistry was awarded to Heeger, MacDiamid and Shirakawa for work in the field. Some organic materials are, of themselves, conducting whereas others only become conducting when subjected to one or more external stimuli. This second type of organic material is known as a semiconductor and is analogous to an inorganic semiconductor in that it may function as either an insulator or a conductor when subjected to one or more external stimuli.
Electrically conducting polymers have the potential to be used in miniaturised electronic components. In particular, organic semiconductors are presently used to form the active element in optoelectronic devices such as organic light-emitting diodes (OLED), organic solar cells, organic field effect transistors (OFET), electrochemical transistors and more recently has been applied to biosensing applications.
Despite recent advances in conducting polymer technology, the full potential of such polymers has not yet been realized in part due to difficulties associated with their processing. In particular, by virtue of their structure, conducting polymers typically exhibit poor physical and chemical properties that inhibit post manufacture processing. For example, the polymers are typically highly conjugated and rigid, which often means that the conducting polymers are intractable solids.
In this respect, desirable new applications for conducting polymers require conducting polymers with superior properties to those presently available. For example, the current state-of-the-art in organic solar cells uses a two component system to achieve efficient charge separation and transport. This system is, however, prone to change with temperature leading to aggregation and changes in device efficiencies. The synthesis of a single component material that cannot aggregate or phase separate is therefore an important area of research. Polymerisation techniques used to synthesise conventional, fully conjugated, semi-conducting polymers typically deliver polymers with a broad molecular weight distribution and offer little, if no, means of control.
Accordingly there remains a need to provide organic conducting or semiconducting materials with greater utility, such as those with improved chemical and physical properties including enhanced solubility.